After 15 years in space, Mir becomes a 140-ton firework display

The demise of the Russian space station, Mir, will begin in earnest shortly after midnight tonight when the first of three rocket "burns" will begin the process of bringing the 140-ton craft crashing into the Pacific Ocean - if all goes to plan.

The demise of the Russian space station, Mir, will begin in earnest shortly after midnight tonight when the first of three rocket "burns" will begin the process of bringing the 140-ton craft crashing into the Pacific Ocean - if all goes to plan.

For the past few weeks Mir has been allowed to descend gradually towards the critical height of 132 miles above ground. At that point, Russian mission control will fire the engines of the Progress cargo ship attached to the station. This will push Mir into the thicker layers of the upper atmosphere where increased friction will slow it down from its orbiting velocity of more than 17,500mph.

On its next pass over Russian territory, a second burn of the Progress rocket engines at 2am will send Mir into an elliptical orbit, slowing the space station even further. Then, at about 5am London time, the final burn of the Progress engine, lasting about 23 minutes, will send Mir into an irreversible descent to its final destination - an area of open sea somewhere between New Zealand and Chile.

Russia's aviation and space agency, RosAviaKosmos, is taking full responsibility for the controlled descent and has taken out insurance of $200m (£140m) to cover accidents. All the rocket burns will take place while Mir passes over Russian territory, to gather as much data as possible about changes to its flight path. Nasa and the European Space Agency are providing tracking and trajectory information gathered from their own space radars.

Most of Mir's 140 tons are expected to burn up during its re-entry into the atmosphere but up to 40 tons could land in the form of 1,500 burning pieces of debris. Colonel Norman Black, of the US Space Command, which tracks satellites, said: "It's 2 billion chances to one that you're go-ing to get struck by this thing."

Mir's solar panels are likely to be the first structuresto break up during its descent, followed by the half-dozenseparate modules that make up the station.

As Mir continues its descent, increased atmospheric friction will cause it to burst into flames. The pressurised modules are expected to buckle and explode when the station reaches a height of about 50 miles. Ten minutes later, the resulting debris should land safely in a mainly uninhabited part of the Pacific Ocean.

Russia has agreed to alter the trajectory of Mir slightly to avoid it passing directly over Japan, but the inhabitants of the Pacific island of Fiji have been warned to stay indoors tonight and its fishermen have been told to avoid touching "foreign objects" if they are out at sea.

Mir has been in orbit for 15 years and, although it has suffered a variety of mishaps, from fires to collisions, it has proved remarkably resilient. Its often-forecast demise marks the end of an era for Russian manned space flight.